1. Field of the Invention:
The present invention relates to a device for automatically mounting and dismounting an upper metal mold to and from a bolster plate and an upper heat plate upon exchange of metal molds when a size and a kind of a tire to be vulcanized are changed in a tire vulcanizing machine.
2. Description of the Prior Art:
In a tire vulcanizing machine, metal molds for vulcanization respectively have different configurations for respective kinds and respective sizes of tires and depending upon a tire production schedule, it is necessary to perform exchange works for metal molds fairly frequently.
An upper metal mold and a lower metal mold were fixed to an upper heat plate and a lower heat plate, respectively, by fastening bolts in the prior art. Since the metal mold exchange work necessitates a long period of time, in recent years plans for improvements thereof have been proposed. One of the proposals is the invention disclosed in Japanese Patent Application No. 60-037704 (1985), and this invention will be described with reference to FIGS. 5 to 9.
In FIGS. 5 to 9, with regard to a metal mold mount portion within a tire vulcanizing machine, in relation to a lower metal mold, on a vulcanizing machine frame 1 a thermal insulator 2 and a lower heat plate 3 are fixedly fastened to the frame by means of bolts 4.
In relation to an upper metal mold, preliminarily a thermal insulator 6 and an upper heat plate 7 are fixedly fastened integrally to a lower surface of a bolster plate 5 by means of bolts 8. The bolster plate 5 is exactly raised and lowered within a frame by means of an elevator and guide means not shown.
Clamp rod 9 is preliminarily assembled as penetrating through holes in the bolster plate 5, the thermal insulator 6 and the upper heat plate 7. At the bottom end of the clamp rod 9 is formed a clamp claw 10, and its top end is fitted to a rotating lever 13 via a key 14. At the middle of a shaft of the clamp rod 9 is mounted a sprocket 11 via a key 12. Furthermore, on the middle portion of the clamp rod 9 is formed a male screw 15, and this male screw 15 is threadedly engaged with a nut 16 which is fixed to the bolster plate 5 by means of bolts 30. Bearings 17 and 18 support the clamp rod 9.
The clamp rods 9 are assembled at four locations at equal intervals on the plane of the bolster plate 5, the respective sprockets 11 are interlocked via a roller chain 19, and thereby rotational drive for the clamp rods 9 is simultaneously transmitted to the clamp rods 9 at four locations.
A sprocket 20 is an idler sprocket for preventing the roller chain 19 from loosening.
Actuation of a cylinder 21 rotationally drives the clamp rod 9 via the lever 13 and the key 14.
A clamp metal 22, a link 23, a lever 24 and a cylinder 25 are used for clamping a lower metal mold 26 and a lower heat plate 3.
A clamp assistant plate 28 is preliminarily fastened to a top surface of an upper metal mold 27 by means of bolts 29, and thus the upper metal mold 27 and the clamp assistant plate 28 are carried into a vulcanizing machine in an integrated state.
When a metal mold is carried into a vulcanizing machine, at first the bolster plate 5, the thermal insulator 6 and the upper heat plate 7 are integrally raised up to the upper limit to broaden a carry-in space for the metal mold, and then, the upper and lower metal molds 26 and 27 and the clamp assistant plate 28 are made to sit at a regular position in the vulcanizing machine 3 by means of a conveying instrument such as a fork-lift or the like. Next, the bolster plate 5 is lowered to bring the upper heat plate 7 into tight contact with the clamp assistant plate 28. At this moment, the clamp claw 10 must be accommodated in the bore of the clamp assistant plate 28 at the position shown in FIG. 8. Then, by actuating the cylinder 25, the clamp metal 22 is meshed with a slot 31 in the lower metal mold 26, and thereby the lower heat plate and the slot 31 are clamped.
Subsequently, the cylinder 21 is actuated to rotate the clamp rod 9, hence the clamp claw 10 is rotated by about 90.degree. as shown in FIG. 9, and the upper heat plate 7 and the clamp assistant plate 28 are clamped. When the clamp rod 9 rotates, the clamp rod 9 is raised by the screw 15, and the upper heat plate 7 and the clamp assistant plate 28 are firmly held in tight contact.
However, the above-described upper metal mold clamp device had the following shortcomings:
(1) In the above-mentioned device, four clamp rods (screw rods) and claws are rotated via a chain by means of a single hydraulic cylinder and thereby an upper metal mold is raised. Accordingly, the rotational angle and the raised height of the screw rod are constant for the four screw rod, and so, there is a shortcoming that if one of the four screw rods should unexpectedly finish to fasten earlier than the others. then the remaining three would become unable to fasten further.
(2) In addition, there is a shortcoming that in the case where before mounting of the upper metal mold the clamp claw should not be well inserted into the clamp bore of the clamp assistant plate but should strike against the top surface of the clamp assistant plate, due to lack of the accommodation means for the clamp claw the weight of the upper heat plate, the bolster plate and the like would be loaded upon the clamp claw, and the claw would be damaged. PA1 (3) Furthermore, since lock means after finishment of clamping of the upper metal mold is not provided, there was a fear that during a work, clamping may loosen and the upper metal mold may fall.